Intravenous (IV) infusion therapy is a widespread medical technique in which fluid nutrients or fluid medicaments are infused into the bloodstream of a patient through an IV tube as part of treating the patient for a particular malady. More specifically, in infusion therapy, one end of an IV tube is connected to a needle and the needle is inserted through the skin into one of the patient's blood vessels. This establishes a path for fluid communication from the IV tube to the blood vessel. The other end of the IV tube is connected to a source of fluid nutrients or medicaments. The fluid nutrients or medicaments are then pumped through the IV tube or drained by gravity through the IV tube into the patient's bloodstream.
While infusion therapy has proven effective in treating a wide range of maladies, it is not without potential complications. One complication, which is of particular concern, is infiltration of the fluid from the IV set into the patient's tissue. More particularly, it sometimes happens that the medical technician who inserts the needle of the IV tube into the patient may fail to properly insert the needle into a blood vessel and instead the needle is inserted into the tissue which surrounds the blood vessel. This results in infiltration of the IV fluid into the patient's tissue.
Infiltration of IV fluid into a patient's tissue can also occur during the course of fluid infusion to a patient even though the IV set was originally established for proper operation. For example, a needle which was originally properly inserted into a blood vessel may nevertheless inadvertently become separated from the blood vessel. This separation can be caused by a number of factors, e.g., patient motion. Of course, in any case wherein the needle is not in fluid communication with the blood vessel, the fluid to be infused will not be infused into the patient's bloodstream, but instead will be infused into the tissue surrounding the blood vessel. In other words, the infusion needle can be dislocated from the blood vessel and consequently cause the infused fluid to become infiltrated into the patient's tissue. The result, in any event, is an abnormal flow of fluid through the IV administration set.
Infiltration of fluid medicaments or nutrients directly into a patient's tissue is undesirable for several reasons. First, certain fluids cannot be efficiently absorbed by the body when the fluid infiltrates tissue. Thus, infiltration of an IV fluid directly into the tissue surrounding a blood vessel can effectively prevent the patient from receiving the prescribed dosage of nutrients or medicament. Second, infiltration of fluids into body tissue can cause considerable pain to the patient and lead to severe complications which could conceivably require amputation or skin grafts.
It is unfortunately the case that in many circumstances, infiltration of IV liquids into a patient's tissue can go unnoticed by hospital personnel for relatively lengthy periods. This is because it is not feasible for medical establishments to routinely provide personnel who can continuously monitor each and every IV infusion procedure that the medical establishment undertakes. Thus, it is desirable to automatically monitor the conduct of IV infusion procedures to ensure that the infused liquid is indeed being infused into the patient's bloodstream and not into the patient's tissue.
Additionally, it is desirable to monitor IV infusion procedures for infiltration without having to reconfigure the IV administration set each time the monitoring evolution is to be conducted. Stated differently, it is desirable to be able to monitor an IV infusion procedure for infiltration without having to periodically open and shut isolation valves in the IV tube in order to permit monitoring of the infusion process. This is because such valve manipulation can be labor-intensive, if done manually, or require relatively expensive electric valve operators, if the manipulation is to be done automatically.
As recognized by the present invention, it is possible to determine whether an IV set is infiltrated into a patient's tissue by monitoring for abnormal characteristics of the flow through the IV set. The present invention accomplishes this by monitoring fluid flow characteristics in the IV set both during the withdrawal of fluid from a patient and during the infusion of fluid to the patient.
Accordingly, it is an object of the present invention to provide a method and apparatus for determining whether an IV infusion set has become infiltrated in a patient's tissue. It is a further object of the present invention to provide a method and apparatus to automatically monitor the conduct of an infusion therapy procedure without requiring reconfiguration of the IV administration set. Yet another object of the present invention is to provide an apparatus which can alarm to indicate the occurrence of IV set infiltration during infusion therapy and alert medical personnel of the infiltration. Finally, it is an object of the present invention to provide an IV set infiltration monitoring method and apparatus that is easy to use and cost-effective to manufacture.